As is well known, the introduction of a scrubbing liquid into a turbulent gas stream to provide intimate mixing of the liquid and gas breaks the liquid up into extremely fine particles which collide and adhere to dust particles and other impurities. Agglomeration of the dust-laden liquid particles or droplets then permits separation of the liquid and the cleansed gas by means of any conventional mist separator. To increase scrubbing efficiency, and specifically to insure intimate mixing of the liquid and gas, venturi systems have been used as shown, for example, in U.S. Pat. Nos. 3,048,956 and 3,350,076.
This invention is concerned with a venturi gas scrubber in which the venturi is formed in an annular shape through which gas and liquid flow in radial directions. The scrubbing liquid is discharged under pressure from a centrally-disposed nozzle which directs the liquid radially and in generally the same plane as the venturi itself. The nozzle may be adjustable to control the discharge of liquid and the walls which define the venturi may also be moved relative to each other to vary the dimensions of the venturi. In one embodiment, the upper wall of the venturi is provided with a trough-shaped top surface, the trough being annular in shape and communicating along substantially its full length with the throat of the venturi passage. Liquid separated from the gas above the upper wall is therefore collected in the trough and recycled through the venturi, resulting in relatively high scrubbing and collection efficiency for the amount of supply liquid, normally water, required by the system.
The annular venturi scrubber of this invention therefore eliminates the use of small nozzles, conserves space, provides a favorable aspect ratio for contact between a gas and a liquid, and, in the embodiment which provides for recycling of liquid, permits a reduction in liquid supply requirements.
Other advantages and objects of the invention will become apparent from the specification and drawings.